One of the methods for drawing a design fastly and delicately on textile and leather materials etc. with a dye is a printing method. The printing method is roughly classified into a method involving platemaking and a method not involving platemaking.
As examples of the printing method involving platemaking, screen printing, roller printing, rotary screen printing, gravure printing and other printing methods using these printing techniques are known, and have been industrially applied. However, in the printing method involving platemaking, the number of colors that can be used is limited for the reason of platemaking. Particularly, in a printing method involving platemaking based on the RGB tricolor separation, although multiple colors can be expressed, there are problems typified by the following (a) to (d).
(a) It is difficult to adjust the hues and densities of the RGB tricolor components.
(b) The reproducibility of print processing results is poor due to multi-layered printing.
(c) Platemaking is costly for small lot production.
(d) It is necessary to prepare color pastes in excess amounts that are more than actually necessary for print processing.
A solution to the above-described problems is a printing method not involving platemaking. In this printing method, a design is printed on a printing substrate using computer-based image processing and formation technologies etc., for example, by ink jet printing with water-based dye inks. The printing method not involving platemaking is classified into a direct printing method, which involves printing a design directly on a printing substrate, and a transfer printing method, which involves printing a design on a paper called a textile printing paper or a transfer paper, followed by transferring the design printed on the paper to a printing substrate.
A novel transfer printing method (hereinafter referred to as “paper printing method”) is publicly disclosed (see, for example, Patent Literature 1) and this method has the following advantages: a textile printing paper has no need for an expensive release agent or a release layer, the textile printing paper can easily be released, a post-printing water washing step produces little water pollution, and the resolution, fastness and color development of a printed design are excellent. The paper printing method described in Patent Literature 1 comprises
a step comprising applying a mixed paste of a water-soluble synthetic binder, a natural glue and an auxiliary agent onto a base paper, drying the base paper to prepare a textile printing paper, and printing a dye ink on the textile printing paper to prepare a printed paper;
a step comprising bringing the printed paper into close contact with a printing substrate and sticking them together under pressure and heat; and
a step comprising performing dye fixing treatment in such a state that the printed paper is kept stuck to the printing substrate, and then removing the printed paper.
The textile printing paper used in the paper printing method described in Patent Literature 1 is obtained by applying a mixed paste of a water-soluble synthetic binder, a natural glue and an auxiliary agent onto a base paper and drying the base paper.